An efficient torque control algorithm for BLDCM with a general shape of back EMF

The authors completely characterize the whole class of the torque control algorithms that enable the brushless DC motors to behave like linear systems but with no torque ripple. The previously known torque control algorithms correspond to either the particular ones in the whole class of the torque control algorithms or their truncated Fourier expansions. The whole class of these torque control algorithms is characterized in the explicit form which contains a function to be chosen freely. This free function can be used to achieve other control objectives such as minimal power loss and maximum constant torque. The authors present the explicit description of the free functions, one for minimal power loss and the other for maximum constant torque under the physical limitation of stator phase currents. To illuminate further the practical significance of this work, the numerical results for four typical shapes of back EMF are presented